HLSC 1200U Lecture Notes - Lecture 3: Stratified Squamous Epithelium, Simple Squamous Epithelium, Simple Columnar Epithelium
Recorded Lecture 3: Chapter 7 Tissues
Definition of tissues: Collection of cells that form a network in a coordinated
fashion to perform a function.
- Composed of cells which are living material, either gives tissue tis function to
produce components of the extracellular matrix
- ECM is a complex nonliving material that surrounds the cell. Intercellular
(between cells) Gives tissue characteristics
Main types of tissues
*Epithelial tissues
- Form membranes that contain and protect the internal fluid environment
- Moves substances in and out of the body and organs; secretion, excretion,
absorption
- Secrete products that regulate functions involved in homeostasis
*Connective tissues
- Connect and holds organs and systems together
- Form structures that support the body and permit movement.
Muscle tissues
- Work with connective tissues to permit movement of body and its parts
Nervous tissue
- Communicate between various parts of the body and in integration of their
activities
- Generation of complex messages that coordinate the body functions.
Extracellular Matrix
- Everything that’s not cells
- Outside of the cell
- Fibres, Water, proteoglycan = compounds that are made up of sugar and
protein.
Components
Structure
Function
Water
H2O
Solvent, provides
fluidity of ECM
Proteins
Structural proteins:
-Collagen fibre
(strength and
flexibility)
- Elastic fibres (Elastic
recoil)
Glycoproteins are
proteins with carb
subunits
- Strength, flexibility,
elastic recoil
- Glycoproteins allow
communication within
the tissue, binds tissue
together structurally
by binding integrins in
the cell membrane or
what we call
intercellular
junctions
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Proteoglycans
Carbs with a protein
backbone
Provide lubrication,
thickens the fluid,
shock absorption
properties,
Epithelial Tissue
Cells close together
- Packed tightly together with desmosomes, (holds cell together) tight
junctions, little interstitial fluid, and ECM
- Protect against: Chemical and mechanical injury, foreign pathogens.
Organized into layers
- Free surface: Interacts with the external environment
- Basement membrane: permeable material linked to underlying tissue.
Basement membrane
- Composed of glycoprotein (protein+carbs): Secreted by epithelial tissue and
connective tissue underneath.
- Integrins (proteins): Part of the cytoskeleton, binds to fibres and strengthen
connections between connective tissue below and epithelial tissue above
Avascular = Blood vessels
- Thickness limits
- No blood vessels
- Blood vessels come through the connective tissue but not to the epithelial
tissue
- The thicker it is, the harder it is for nutrients to get up to the most superficial
layer.
- Limits nutrients and waste exchange.
- Limits the lifespan of the tissue.
Capable of reproduction
- Necessary
- Wear and tear against mechanical and chemical injury
Types and locations
Membranous epithelium (covering or lining)
- Covers the body and parts: lines the serious cavities, loood and lymphatic
vessels and respiratory, digestive, and genitourinary tracts
Glandular Epithelium
- Secretory units of endocrine and exocrine glands
Functions
Protection
- Protect us from mechanical and chemical injury, foreign particles
Sensory functions
- Adapted for sensing changes in environment (skin, nose)
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Absorption
- Of digestive material
- Gas exchange
Secretion
- Kidneys, urine is excreted
Cell shapes:
Flat= squamous
Cube= Cuboidal
Tall= Columnar
Stratified means more than one layer. (2 or more layers)
Stratified squamous = The most superficial cells are flat.
Stratified cuboidal = The most superficial are cubed shaped.
Pseudo means fake
Pseudostratified The nucleus of the cells are at different levels. It looks like it has 2
or more layers, but it actually has one.
Single Layer epithelium
Simple squamous epithelium
- Characteristic: permeable to many substances
- Location: Endothelium (blood and lymphatic) vessels; mesothelium, (pleura,
pericardia, peritoneum), kidney (glomerulus), alvelolar (lung)
Simple cuboidal epithelium
- Location: many glands and ducts, eg kidney.
Simple columnar epithelium
- Location: often lines hollow visceral structures, digestive tract, uterus,
respiratory tract
- Characteristic: cells often modified for certain functions: goblet cells
(secretion), cilia (movement), microvilli (absorption)
Pseudostratified columnar epithelium
- Characteristic: columnar cells of differing heights; all cells rest on basement
membrane but may not reach the free surface above; cell nuclei at odd and
irregular levels. Can contain cilia and goblet cells
- Location: air passages, segments of male reproductive system.
Modified simple columnar epithelium
Modifications
Location
Function
Ciliated
Respiratory tract
Propel surface along free
surface of tissue
With microvilli
Small intestine
Tiny projections,
sometimes called the
brush border Digestive
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Document Summary
Definition of tissues: collection of cells that form a network in a coordinated fashion to perform a function. Composed of cells which are living material, either gives tissue tis function to produce components of the extracellular matrix. Ecm is a complex nonliving material that surrounds the cell. Form membranes that contain and protect the internal fluid environment. Moves substances in and out of the body and organs; secretion, excretion, absorption. Secrete products that regulate functions involved in homeostasis. Connect and holds organs and systems together. Form structures that support the body and permit movement. Work with connective tissues to permit movement of body and its parts. Communicate between various parts of the body and in integration of their activities. Generation of complex messages that coordinate the body functions. Fibres, water, proteoglycan = compounds that are made up of sugar and protein.
